1. Field of Invention
The invention relates to a control apparatus and a control method for a hybrid vehicle.
2. Description of Related Art
A split, hybrid vehicle has been conventionally provided in which an engine, two electric motors, and a planetary gear unit, as a differential gear device, are provided. Three gear elements of the planetary gear unit are connected to the engine, one of the electric motors and an output shaft, respectively, and the other electric motor and the output shaft are connected (see Japanese Patent Application Laid-Open No. HEI 10-98805).
For example, when an accelerator pedal is depressed so that the rotation of one gear element of the various gear elements of the planetary gear unit changes, the rotation speed of one of the electric motors changes. Therefore, a design is provided such that a target motor torque of the other electric motor is set, taking the inertial torque of the one of the electric motors into consideration. Hence, the drive feeling of the hybrid type vehicle can be improved.
However, in the aforementioned conventional hybrid type vehicle, more specifically, in the case of a split, hybrid vehicle in which the planetary gear unit has four gear elements, and the gear elements are connected to the engine, the two electric motors, and the output shaft, respectively, the drive feeling of the hybrid type vehicle deteriorates, for example, in a situation where, when the accelerator pedal is depressed so that one of the gear elements of the planetary gear unit, for example, the gear element connected to the engine, changes in rotation speed, the two motors, which change in rotation speed with changes in the rotation speed of the gear element, are not properly controlled.
Accordingly, it is an object of the invention to provide a control apparatus and a control method for a hybrid type vehicle, more specifically, a split, hybrid vehicle in which a differential gear device has four gear elements that are connected to an engine, two electric motors, and an output shaft, respectively, the control apparatus and method avoiding deterioration in the drive feeling of the hybrid vehicle when the rotation of a gear element of the gear elements of the differential gear device changes.
To achieve the aforementioned and other objects, a hybrid vehicle control apparatus in accordance with the invention includes an engine; first and second electric motors; an output shaft connected to a drive wheel; a differential gear device having at least four gear elements that are connected to the engine, the first and second electric motors, and the output shaft, respectively; generated control torque calculation processing means for calculating a control torque generated in association with an electrical control of the second electric motor; inertia torque calculation processing means for calculating first and second inertia torques occurring in association with changes in motor rotation speeds of the first and second electric motors; target control torque calculation processing means for calculating a control torque serving as a target for performing an electrical control of the first electric motor, based on the control torque and the first and second inertia torques; and torque control processing means for performing a torque control of the first electric motor in accordance with the control torque serving as the target.
Another hybrid vehicle control apparatus in accordance with the invention includes an engine; first and second electric motors; an output shaft connected to a drive wheel; a differential gear device having at least four gear elements that are connected to the engine, the first and second electric motors, and the output shaft, respectively; generated control torque calculation processing means for calculating a control torque generated in association with an electrical control of the second electric motor; inertia torque calculation processing means for calculating a first inertia torque that occurs in rotational elements from a rotor of the first electric motor to a gear element of the differential gear device in association with a change in a motor rotation speed of the first electric motor, and a second inertia torque that occurs in rotational elements from a rotor of the second electric motor to a gear element of the differential gear device in association with a change in a motor rotation speed of the second electric motor; target control torque calculation processing means for calculating a control torque serving as a target for performing an electrical control of the first electric motor, based on the control torque and the first and second inertia torques; and torque control processing means for performing a torque control of the first electric motor in accordance with the control torque serving as the target.
Still another hybrid vehicle control apparatus in accordance with the invention includes an engine; first and second electric motors; an output shaft connected to a drive wheel; a differential gear device having at least four gear elements that are connected to the engine, the first and second electric motors, and the output shaft, respectively; target output torque calculation processing means for calculating a target output torque of an output torque outputted to the output shaft; generated control torque calculation processing means for calculating a control torque generated in association with an electrical control of the second electric motor; inertia torque calculation processing means for calculating first and second inertia torques occurring in association with changes in motor rotation speeds of the first and second electric motors; target control torque calculation processing means for calculating, based on the control torque and the first and second inertia torques, a control torque serving as a target for performing an electrical control of the first electric motor such that the target output torque is generated; and torque control processing means for performing a torque control of the first electric motor in accordance with the control torque serving as the target.
A yet another hybrid vehicle control apparatus in accordance with the invention includes an engine; first and second electric motors; an output shaft connected to a drive wheel; a differential gear device having at least four gear elements that are connected to the engine, the first and second electric motors, and the output shaft, respectively; target output torque calculation processing means for calculating a target output torque of an output torque outputted to the output shaft; generated control torque calculation processing means for calculating a control torque generated in association with an electrical control of the second electric motor; inertia torque calculation processing means for calculating a first inertia torque that occurs in rotational elements from a rotor of the first electric motor to a gear element of the differential gear device in association with a change in a motor rotation speed of the first electric motor, and a second inertia torque that occurs in rotational elements from a rotor of the second electric motor to a gear element of the differential gear device in association with a change in a motor rotation speed of the second electric motor; target control torque calculation processing means for calculating, based on the control torque and the first and second inertia torques, a control torque serving as a target for performing an electrical control of the first electric motor such that the target output torque is generated; and torque control processing means for performing a torque control of the first electric motor in accordance with the control torque serving as the target.
The hybrid vehicle control apparatus of the invention may further include target engine revolution speed calculation processing means for calculating a target engine revolution speed of the engine; and rotation speed control processing means for performing a rotation speed control of the second electric motor such that an engine revolution speed becomes equal to the target engine revolution speed.
In the hybrid vehicle control apparatus of the invention, if the target engine revolution speed is NE* and the vehicle speed is V, a target motor rotation speed NM2* may be given as:
NM2*=K1xc2x7NE*xe2x88x92K2xc2x7V (K1, K2: constants). 
In the hybrid vehicle control apparatus of the invention, the first inertia torque may be calculated by multiplying an inertia moment of a rotor of the first electric motor by an angular acceleration of the first electric motor, and the second inertia torque may be calculated by multiplying an inertia moment of a rotor of the second electric motor by an angular acceleration of the second electric motor.
In the hybrid vehicle control apparatus of the invention, the first inertia torque may be a sum of values obtained by multiplying inertia moments of the rotational elements from the rotor of the first electric motor to the gear element of the differential gear device by angular accelerations of the rotational elements, respectively, and the second inertia torque may be a sum of values obtained by multiplying inertia moments of the rotational elements from the rotor of the second electric motor to the gear element of the differential gear device by angular accelerations of the rotational elements, respectively.
In the hybrid vehicle control apparatus of the invention, if the control torque generated in association with the electrical control of the second electric motor is TM2#, the first inertia torque is IM1, the second inertia torque is IM2, and the target output torque is TO*, the target motor torque TM1* may be given as:
TM1*=K3(TM2#+IM2)xe2x88x92K4xc2x7TO*xe2x88x92IM1 (K3, K4: constants) 
A hybrid type vehicle control method in accordance with the invention is applied to a hybrid vehicle that has an engine; first and second electric motors; an output shaft connected to a drive wheel; and a differential gear device having at least four gear elements that are connected to the engine, the first and second electric motors, and the output shaft, respectively.
In the method, a control torque generated in association with an electrical control of the second electric motor is calculated. First and second inertia torques occurring in association with changes in motor rotation speeds of the first and second electric motors are calculated. A control torque serving as a target for performing an electrical control of the first electric motor is calculated based on the control torque and the first and second inertia torques. A torque control of the first electric motor is performed in accordance with the control torque serving as the target.